It looks as though the Fallout: New Vegas patch on Xbox 360 is in need of a patch, so you may wish to hold off on updating your game for the time being.
Bethesda updated users on the forum with this:
“The update for English versions of the game should be going live later tonight. Exact time is TBA, but it’ll probably be later in the night. For folks playing the game in other languages, the wait is going to be a little longer.
“For now, if your game save is working properly after getting the “missing content” notice, here’s what we suggest. Load your game save after getting the message about missing content. Once you’re in the game, make a new game save, and moving forward you shouldn’t have any issues. Once the new title update is up, you can then go back to your older save files.
“If your game is crashing after loading the “missing content” save, you’ll want to wait until this new update goes live.”
An estimated time for the fix will be posted when the developers know more, so keep watching the forum.
Earlier today, Bethesda tweeted: “We’re aware some folks are having New Vegas save issues. We’re working with Microsoft on this and should have more information soon.”
Bethesda also suggested folks “decline the update,” until a fix for the fix was issued – and you may still wish to keep that in mind just to save yourself some trouble.